1. Field of the Invention
The present invention relates to a beam recording apparatus in which a recording member is scanned by plural beams to record the traces of beam irradiation on said recording member.
2. Description of the Prior Art
In the conventional apparatus for information recording on the recording medium by means of successive scanning thereon with a single beam, the transmission speed of the information signals for modulating the beam has to be increased for a high-speed recording. Also there is required a faster scanning function which may correspond to several ten thousand revolutions per minute of the polygonal rotary mirror if the scanning function is achieved by such a mirror. For this reason such recording apparatus has a structural limitation in the high-speed recording.
In order to avoid such drawback there has been proposed a recording apparatus, in which, as disclosed in the U.S. Pat. No. 4,000,493, a recording medium is simultaneously scanned by plural beams respectively modulated with recording signals.
In such apparatus, the position of all the beams can be easily detected from the position of any one beam if all the beams B1-B4, as shown in FIG. 1A, are positioned perpendicular to the beam scanning direction SL, whereby the control for example for the start of modulation can be significantly facilitated.
However in such perpendicular arrangement of beams with respect to the scanning direction or line SL the distance of the beams has to be equal to and thus gives a limitation to the distance of pixels to be formed on the recording medium.
On the other hand, as shown in FIG. 1B, a beam distance Pl larger than the pixel distance Ps is permissible if the beams are inclined by an angle .theta. with respect to a line L--L' perpendicular to the scanning direction, but the characters etc. appear in inclined abnormal form if the conventional beam modulation control is applied to such beams of inclined arrangement.